Variable capacity type vane pump with a variable restriction orifice

A vane pump of the type having a variable capacity, comprising:

• a cam ring;
• a rotor placed for rotation within the cam ring, the rotor having a number of radial slots, and vanes placed for radial inward and outward movement in the respective slots each having a bottom;
• a pump chamber defined between the cam ring and the rotor, the pump chamber having an inlet through which fluid is introduced into the pump chamber and an outlet through which pressurized fluid is discharged from the pump chamber;
• a pot connected to the bottom of at least one of the slots having vanes moving inwardly in the respective slots;
• a conduit connected at its one end to the port and at the other end thereof to the outlet of the pump chamber;
• a restriction orifice placed in the conduit;
• and
• means for moving the cam ring with respect to the rotor to vary the capacity of the vane pump in response to a pressure differential across the restriction orifice.